Elephant Toothpaste

Have you ever made elephant toothpaste? It is super fun to watch and and play with. I can’t believe as a chemistry teacher I have never done this experiment before… until now. It’s pretty easy to do, though the materials may not already be in your home, they are easy to acquire.

Here’s what you’ll need to get started:

A large dish or foil pan

Dry Active Yeast packet

Warm water

Tall vase, carafe or long neck bottle

Measuring cup and measuring spoon

Dish soap

Food coloring (optional)

Hydrogen Peroxide (at least 6% available for about $3 at a Beauty Supply Store)

I had the tots first touch the yeast. It looked like sand to them. They also noticed that it had a strong odor.

Next, we measured 1 Tbsp of dry active yeast and added it to about 3Tbsp of warm water.

We mixed it and put it aside for a few minutes. This does not have to be exact.

Next we used a tall clear glass bottle (a clear wine bottle or carafe is actually perfect!) and added about 1/2 cup of hydrogen peroxide. Add some food coloring if you want to.

I recommend using glass as the reaction can get quite warm. Add a few good squirts of dish soap.

Be sure not to use one with the antibacterial beads. The beads will interfere with the reaction. Give it a good swirl.

Place the bottle in the large dish pan. I added the yeast to the bottle and watched the magic unfold!

In class, I then had the tots sit away a bit and put their safety glasses on. There was plenty of oohing and aahing! The kids thought it was great, especially after our discussion of whether elephants need toothpaste:)

After the reaction ended, I invited the children to touch the foam.

It was warm and bubbly and soft. We also touched the bottle and it was very warm as well. (Just make sure you touch the foam and the bottle first to make sure it isn’t too hot for the kiddos).

The Science Behind the Activity:

When the yeast mixture is added to the hydrogen peroxide, it helps to facilitate a decomposition reaction (a reaction that breaks a chemical compound down). In this case, hydrogen peroxide (H2O2) is being broken into water (H2O) and oxygen gas (O2). The yeast acts as a catalyst (kind of like a chemical “helper”) to make the reaction go faster. Because of the addition of dish soap, the oxygen gas gets trapped in the soap as bubbles and creates the foam that you see. This reaction also releases heat which makes it an example of an exothermic reaction. So much chemistry in this fun little demonstration.

Extension:

Test out different concentrations of hydrogen peroxide. How does concentration affect the rate of the reaction?

Test whether the yeast needs to be mixed with water first or if it can be added directly

Test whether the amount of yeast added affects the reaction

What happens if the yeast is added to cold water? Does temperature matter?